Three weeks ago DD (18 months) started breaking out in hives at daycare one day, and the following morning was absolutely covered in them. We took her to the doc, who just said to give benedryl, and they gradually receded. She was still getting about one a day even last week.

This morning, just when I thought they were gone for good, she had more, big ones, only on her belly (but huge, inches long, and probably 5-7 of them).

I had thought, when they went away, they were viral (there's been a lot of icky stuff in our house: DS had scarlet fever, DD had a tummy bug, we all have colds) but these new ones make me think otherwise.

My current plan is to write down everything she eats every day and whether she has hives or not and hopefully a pattern will emerge.

When I had hives, I tracked it to laundry detergent and/or dryer sheets. You may also want to look at soap/lotion - anything that comes in contact with skin or is taken internally. It's really hard to pinpoint!

What worked the best for me for itching was baking soda/water paste. It flakes off and makes a mess, so naked time may be required.

Sorry she's going through this! It is really uncomfortable and I hope she feels better soon.

My youngest son is hivey as well. We went through five days of hives which benadryl did nothing for, he had two different steroid treatments, then he had swelling in his throat and face which resulted in an ER visit. Our ped then recommended we have allergy testing done to see if he was allergic to anything. We are also still nursing. My oldest and I are allergic to a bunch of things, so we already had ruled out a lot of food allergens and things like soap/detergents/etc.

Basically, he's not allergic to anything from what the skin prick and blood tests show. The allergist said she thought his hives might be immunologically caused - meaning, for some reason whenever his immune system gets triggered it sends out a massive histamine surge which results in the hives. It usually starts in kids around this age, and can last for a few years.

We got an epi-pen (due to the scary throat swelling incident), and were told if he was having hives daily we could try giving him zyrtec to help reduce the histamine attack. Otherwise, we could keep with the benadryl when he broke out in a hive rash.

So sorry to hear about your dc. Can I ask how you knew they were in the throat? I worry I would miss that. DD isn't that bad. Even that first day when they were worst they mostly cleared up by afternoon without any meds. I think I may have tied them to some hand me down clothes I let her wear without washing.
She still gets a hive here and there-- mostly after crying! But it only lasts a few minutes.

This makes sense to me, as heat brings out hives even days after exposure to whatever it was that initially triggered the hives. I had an allergic reaction to medication several years ago, and although I promptly stopped taking it when I realized it was causing hives, I continued to break out for at least 7 days afterward, whenever I showered or ran on the treadmill. I imagine crying is the same sort of activity that raises body temperature. I hope that once these subside, she's done with her hives and feels better.

Have you considered dermatographism. It's not very uncommon, affecting something like 2% of the population.

We had several instances of unexplained hives and eventually went to an allergist. He did the skin test and found her reacting to everything including the saline control. So he ran a finger nail down her back and her whole back erupted in hives.

Turns out that she breaks out in hives even to pressure. So she was going to daycare and laying on top of the bedspread at nap time. The seams in the bedspread were causing hives on her stomach, back, sides, buttocks, and thighs.

We chose to just be aware of it for a while and not medicate. Just treat hives with a topical cream. But it soon became clear that she may have other allergies as well and we ended up putting her on a daily oral antihistamine.

The allergist did say that the majority of hives in kids are virus and that most of the time no explanation is every found for hives in children.

Have you considered dermatographism. It's not very uncommon, affecting something like 2% of the population.

I actually did try that, thanks for mentioning it though. She didn't react to me scratching her.

I do think it may have been the clothes--whether it was the other family's different detergent or the fact they have cats. We were at their hoiuse and she got a hive on her face while we were there (though obviously she may have had others under her clothes) and she hadn't been crying... so maybe the cats? It, again, only lasted a few minutes.